Voltage converters are widely used in engineering as power supplies and voltage stabilizers. The construction of each voltage converter consist of reactive energy storage (inductive and capacitive elements) and a switching device. With the development of semiconductor technology, it is possible to abandon mechanical switching devices, and to use semiconductor diodes, transistors, and thyristors as switching elements, which switching frequency can reach several hundred kilohertz. The main problem associated with the control of semiconductor voltage converters is to stabilize the output voltage depending on the input voltage and a variable power consumption load. The article deals with the control problem of a voltage buck-converter under the specified conditions. The non-linear discontinuous control law is developed in the article, which allows to stabilize the output voltage under conditions of unknown input voltage and output load current. The basic idea is based on the base of the so-called “vortex algorithms”, which provides invariance with respect to external unmatched perturbations. Theoretical results can be implemented with using modern pulse-width modulation converters. Simulation results shows the efficiency of the developed algorithms.